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Flywheel casting number help

Discussion in 'The Garage' started by 79Jimmy, Jul 13, 2004.

  1. 79Jimmy

    79Jimmy 1/2 ton status

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    I recently aquired this flywheel in the hopes it was for a 400 to be used in the 383 I'm building. The casting number is 3973457N GM2 113V . I've searched the net to the best of my ability but no luck /forums/images/graemlins/dunno.gif so I thought I'd utilize the bottomless knowlege and resources of CK5 /forums/images/graemlins/1zhelp.gif

    James
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    If its a 400 smallblock one it will have a counterweight cast into it(manual tranny flywheel)or a balance weight welded to it if its an automatic flexplate--I'll try looking that number up for you and post back later--I have a dealers parts counter book that covers up to 1972,I'll see if it shows up in there...
     
  3. 79Jimmy

    79Jimmy 1/2 ton status

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    Thanks. It does have a counterweight cast into the back oposite the casting number, it's just over 14" across the ring gear, about 13.5 across the face and its a 6 x 3.5" crank bolt pattern. I just for the life of me cant reference this casting number anywhere! Could it be aftermarket even with the "GM2" cast into it?
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    I looked at all my books,no number that matches that one you listed--I stopped at the local junkyard and looked in their hollander interchange book--only number close to yours is 3973452 --thats a manual tranny flywheel for all the other small blocks except the 400,with a 10-1/2 inch clutch-.I assume we are talking a manual flywheel--I have one from a 72 350,it has two small "bumps" on the motor side that could be easily mistaken for counterweights,if you look at the back of the flywheel the bumps will be at the 4 o clock and 8 o clock positions if you hold the wheel with the bumps toward the bottom of the wheel--I'd make absolutely sure its the right one before you install it,since the wrong one will make it shake itself to death!.
    Does a 383 motor need the externally balanced 400 flywheel,or is it rebalanced internally??(not that familiar with that build up-- /forums/images/graemlins/dunno.gif)I bought a 3+3 crew cab truck for 300 bucks a long time ago that was sitting at a gas station for months,the owner refused to pay the mechanic for installing another motor because he claimed it was "junk" a because it vibrated real bad--turned out the guy put a 400 smallblock in it,and thought it was a 350,and used the flexplate from the 350--I saw the problem right away when I noticed the harmonic balancer was counterweighted,and the flex plate was not(no inspection cover!)--I played dumb while I bought it--got a good truck cheep! /forums/images/graemlins/grin.gif
     

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